r324062 - [Sema] Add implicit members even for invalid CXXRecordDecls

[Eric Fiselier via cfe-commits]

This causes some stray diagnostics to be emitted in certian cases where a
base class is already invalid:

Reproducer: https://gist.github.com/EricWF/588a361030edeaebbbc1155b8347cab0

On Fri, Feb 2, 2018 at 1:40 AM, Ilya Biryukov via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> Author: ibiryukov
> Date: Fri Feb  2 00:40:08 2018
> New Revision: 324062
>
> URL: http://llvm.org/viewvc/llvm-project?rev=324062&view=rev
> Log:
> [Sema] Add implicit members even for invalid CXXRecordDecls
>
> Summary:
> It should be safe, since other code paths are already generating
> implicit members even in invalid CXXRecordDecls (e.g. lookup).
>
> If we don't generate implicit members on CXXRecordDecl's completion,
> they will be generated by next lookup of constructors. This causes a
> crash when the following conditions are met:
>   - a CXXRecordDecl is invalid,
>   - it is provided via ExternalASTSource (e.g. from PCH),
>   - it has inherited constructors (they create ShadowDecls),
>   - lookup of its constructors was not run before ASTWriter serialized
>     it.
>
> This may require the ShadowDecls created for inherited constructors to
> be removed from the class, but that's no longer possible since class is
> provided by ExternalASTSource.
>
> See provided lit test for an example.
>
> Reviewers: bkramer
>
> Reviewed By: bkramer
>
> Subscribers: cfe-commits
>
> Differential Revision: https://reviews.llvm.org/D42810
>
> Added:
>     cfe/trunk/test/Index/Inputs/crash-preamble-classes.h
>     cfe/trunk/test/Index/crash-preamble-classes.cpp
> Modified:
>     cfe/trunk/lib/Sema/SemaDecl.cpp
>
> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/
> SemaDecl.cpp?rev=324062&r1=324061&r2=324062&view=diff
> ============================================================
> ==================
> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Fri Feb  2 00:40:08 2018
> @@ -15440,10 +15440,10 @@ void Sema::ActOnFields(Scope *S, SourceL
>                                            CXXRecord->getDestructor());
>          }
>
> -        if (!CXXRecord->isInvalidDecl()) {
> -          // Add any implicitly-declared members to this class.
> -          AddImplicitlyDeclaredMembersToClass(CXXRecord);
> +        // Add any implicitly-declared members to this class.
> +        AddImplicitlyDeclaredMembersToClass(CXXRecord);
>
> +        if (!CXXRecord->isInvalidDecl()) {
>            // If we have virtual base classes, we may end up finding
> multiple
>            // final overriders for a given virtual function. Check for this
>            // problem now.
>
> Added: cfe/trunk/test/Index/Inputs/crash-preamble-classes.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Index/
> Inputs/crash-preamble-classes.h?rev=324062&view=auto
> ============================================================
> ==================
> --- cfe/trunk/test/Index/Inputs/crash-preamble-classes.h (added)
> +++ cfe/trunk/test/Index/Inputs/crash-preamble-classes.h Fri Feb  2
> 00:40:08 2018
> @@ -0,0 +1,9 @@
> +struct Incomplete;
> +
> +struct X : Incomplete {
> +  X();
> +};
> +
> +struct Y : X {
> +  using X::X;
> +};
>
> Added: cfe/trunk/test/Index/crash-preamble-classes.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Index/
> crash-preamble-classes.cpp?rev=324062&view=auto
> ============================================================
> ==================
> --- cfe/trunk/test/Index/crash-preamble-classes.cpp (added)
> +++ cfe/trunk/test/Index/crash-preamble-classes.cpp Fri Feb  2 00:40:08
> 2018
> @@ -0,0 +1,8 @@
> +#include "crash-preamble-classes.h"
> +
> +struct Z : Y {
> +  Z() {}
> +};
> +
> +// RUN: env CINDEXTEST_EDITING=1 \
> +// RUN: c-index-test -test-load-source-reparse 5 local -I %S/Inputs %s
>
>
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